


Little Brother

by Lady_Zephyrine



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Baby Brother Sans, Big Brother Papyrus, Brotherly Love, Family Fluff, Fell!Papyrus has a cat, Gen, I might add more tags in the future, Underfell Papyrus, Underfell Sans, Undertale AU
Language: English
Status: In-Progress
Published: 2017-05-26
Updated: 2017-08-24
Packaged: 2018-11-05 01:53:24
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 3,487
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11003532
Author URL: https://archiveofourown.org/users/Lady_Zephyrine/pseuds/Lady_Zephyrine
Summary: Papyrus manages to find a helpless infant during his patrols. With nobody else around to take care of it, Papyrus decides to take it in.





	1. Chapter 1

**Author's Note:**

> So this is sort of a small thing I started to work on. While I prefer to have the skelebros as twins, I still have a soft spot for Big Brother Papyrus. Also, Papyrus is 13 in this story, just so we're clear.
> 
> Anyways, I hope you guys enjoy this.

It was yet another cold morning. The wind was blowing, the dogs were howling. On days like this, monsters would rather stay indoors...Besides the Royal Guard, of course. Unless there was an extreme blizzard outside, the Royal Guard was required to stay at their stations.

As a trainee, Papyrus was already used to this. But it wasn’t all bad. Ever since he ran away from New Home, he managed to find a safer place in Snowdin. Unlike those who lived in the city, the monsters here rarely got into any serious fights. Instead, there was always a lot of rough housing. It amused Papyrus how in such a cruel world, these monsters could still find ways to enjoy themselves. For a moment, he wondered if there were any nice places on the surface. He quickly disregarded the thought, humans were supposed to be cruel. There was a reason why King Fluffybuns wanted them dead!

And yet...even a place as “calm” as Snowdin (for lack of better words), Papyrus couldn’t help but feel a sense of dread hanging over him. Perhaps it was the fear of his father finding him and telling him how much of a disgrace he is? Or maybe it was the fear of a human walking by and killing the entire town? He wasn’t entirely sure, all he knew was that it was best to keep his guard up at all times.

Something red caught Papyrus’ eye. He crept over the the river, only to find that red clothes were scattered all over the river bank...along with some dust. Papyrus gave the dust a sympathetic look.

 **“It looks like you couldn’t make it, huh?”** Papyrus let out a soft chuckle. **“I don’t blame you. The Underground isn’t really a place for the weak.”**

It was then that Papyrus noticed some movement under the clothes. When he lifted the coat, he managed to find a small skeleton rattling in the dust. The skeleton appeared to be a newborn, it had large fontanelles on its skull,  it couldn't even make a sound.

 **“...How long have you been laying there?”** Papyrus asked as he picked up the infant, **“And where did you even come from?”**

The infant attempted to make a noise, it curled up against Papyrus for protection as it rattled...Wait, it wasn't just rattling, it was SHAKING. As much as he hated to admit it, Papyrus was scared for the little guy. It would probably be better to leave the kid here to die. And yet...the very thought made Papyrus’ soul quiver. Perhaps he could take it in for now? Undyne and those dogs might tease him for it, but it didn't matter as long as this infant survives the night...That is, IF it survives the night.

Papyrus wrapped the infant in his scarf as he started heading into Snowdin. He held it close to his chest, he could tell that a blizzard was going to happen any minute now. Not even a human would be foolish enough to be outside in a blizzard like this!

 

* * *

 

As Papyrus made his way through Snowdin, the wind had started to get worse. It felt like he was going to be blown away, but somehow he was able to make it home unscathed. He leaned against the door with the infant still in his arms. It stopped shaking a little while ago, he worried that it had fallen down. Surprisingly, it was still breathing. Perhaps now was a good thing to check on its stats?

_**COMIC SANS** _

_**ATK- 1** _

_**DF- 1** _

_**HP- 1** _

Papyrus stared at the infant in astonishment. It was this weak and it STILL survived staying out in the snow? Granted, it probably would’ve become dust if Papyrus hadn’t shown up sooner. But still, it was hardier than it looked.

 **“So your name’s Comic Sans?”** Papyrus snorted, **“That’s a dumb name if I’ve ever heard one!”**

The infant stirred, it gazed at Papyrus with its large eye sockets. It couldn’t speak, but Papyrus could tell that it felt safer here. He felt a sense of accomplishment wash over him like a rainstorm...or in this case, a snow storm.

 **“...You know what? How about I just call you ‘Sans’, Instead? I know it’s a common nickname among us skeletons, but it’d be better than using your full name.”** The tall skeleton began to smile. **“And besides, the only other skeleton I know who would choose that name is my father. And we don’t want him around, do we?”**

Sans continued to look at the older skeleton, he began to rattle, again. This time, the rattling was calmer then it was before. It was expected, since he's still a newborn.

 **“Oh, you’re probably hungry!”** Papyrus said as he sat up and headed into the kitchen. He didn’t have any bottles available to him, and using a cup would make a mess. He dug through the junk drawer until he found a turkey baster. It was a weird idea to use a turkey baster to feed an infant, but it’ll have to do.

He placed Sans onto the table and headed over to the fridge. He pulled out a milk carton and placed it onto the counter. When he got the milk into the turkey baster, he walked back over to Sans and started feeding him the milk. He practically chugged it down, it was like he hadn’t eaten anything in months. As soon as he was done, he started to doze off.

Papyrus lifted the infant and started leaving the kitchen, he began to take Sans upstairs. **“Come on, let’s get you bundled up!”** He walked into his room, it was a tidy little room with a race car bed in the corner. On the bed was a cat, which was curled up into a ball. Papyrus placed Sans next to the cat, it groggily raised its head.

 **“Keep an eye on him, Doomfanger!”** Papyrus said in a commanding tone, **“I need to find something warmer for our guest!”**

Doomfanger looked around the room with his eyes half-open. He let out a yawn before walking out of bed.

 **“Fine, be that way!”** Papyrus yelled. He started digging through his closet, he looked through some old clothes, none of which would fit an infant. Finally,  he decided to pull out a soft, pink blanket. It wasn’t much, but it would have to do. He walked back over to Sans, who was looking over at his direction. Papyrus took his scarf back and wrapped Sans in the blanket.

 **“There, you should be a little warmer in this.”** Papyrus said as he finished wrapping Sans up. He looked snug, like a cat curled up in a box. Sans stared at Papyrus, the older skeleton picked him up and took him downstairs. He sat on the couch and grabbed the remote, turning the TV on as he held Sans closely to his chest. Papyrus knew that he was going to be staying up all night, but that didn't matter to him. After all, sleep was for the weak!

Of course...Sans was _very_ weak, he needed as much sleep as he could get. Papyrus could already feel Sans' breathing slow down. He gently ran his sharp phalanges along the back of Sans' skull. They weren't sharp enough to scratch anybody, but Papyrus was careful nonetheless.

He held onto Sans for the rest of the night, he was going to keep this infant safe no matter what.

**Notes for the Chapter:**

> So a couple of thing I should mention.
> 
> 1\. Since skeletons don't have vocal chords, I'd imagine that newborn skellies rattle in order to get someone's attention. The reason for this is because their magic isn't fully developed. It'll take them 2-3 months until they can actually "vocalize".
> 
> 2\. The turkey baster idea actually came from one of Zarla's comics. To be fair, I don't think Pap would have any baby bottles lying around.
> 
> 3\. Of course, Doomfanger became a thing after the Underfell Demo was released by Maniaknight. Plus, I love the idea that Fell!Papyrus has a cat.


	2. Chapter 2

...Papyrus must have dozed off at some point, as all that he could hear was the static on the TV and the long, drawn-out meows of his beloved cat.

 **"OK, Doomfanger! I'll get your food in a minute!"** Papyrus looked down at Sans, he was chewing on his own blanket. Of course! Baby bones needed to eat all the time, didn't they?

Papyrus walked into the kitchen, he placed Sans onto the table. The smaller skeleton watched as Papyrus reached into the cupboard, he poured cat food into a bowl for Doomfanger. Sans huffed, he began to rattle again.

 **"Sans, please be patient!"** Papyrus scolded, though he knew Sans wouldn't understand him anyway. He made his way over to the refrigerator and pulled out a carton of milk. He washed out the turkey baster he used yesterday before filling it with milk again.Before he could feed Sans, his cell phone started to ring. Papyrus huffed, he pulled out his phone and answered it. **"Hello?"**

"Where ARE you right now?!" yelled an aggressive voice. Again, Papyrus couldn't help but sigh. He grabbed the turkey baster with one hand while holding the phone with the other hand." **I'm sorry, Undyne. I've been busy with something."**

"HOW!?" Undyne yelled. "YOU'RE NEVER BUSY WITH ANYTHING!?"

 **"That's because..."** Papyrus tapped his fingers against the table. He could lie to her about what happened yesterday, but what was the point in that? Papyrus cleared his non-existent throat. **"Well, I found a monster at the river bank yesterday. He was laying in a pile on dust, but that's about it."**

"So let me guess, you've taken the monster in?" Undyne asked. Papyrus nodded, despite Undyne not being around. **"Yes, he's laying down on the table right now."**

Undyne paused for a moment. She began to speak in a confused tone. "Well...I'll get the dogs to take a look at the river bank. In the meantime, I'm coming over to your house!"

**"Um, that isn't really-"**

"Too late, I'm coming over right now!" Undyne said before she hung up. Papyrus let out a sigh, he walked over to Sans and started feeding him the milk. **"I guess you'll get to meet my boss. She can be kind of harsh, so try to behave yourself when she comes over. OK?"**

After Sans had guzzled down the milk, he began to doze off. Papyrus picked him up and held him close to his chest. **"Well...I suppose that's one way to behave."**

As soon as Papyrus sat down, the door suddenly flew into the kitchen. He could've sworn he saw Doomfanger run outside afterwards. When he looked at the door frame, A blue fish monster had walked in. Like everyone else in the Underground, her clothes were black and red.

"All right, Papyrus...Where is he?"

 **"He's right here,"** Papyrus said, revealing Sans to Undyne. She stared at him for more then a minute, she was starting to make Sans uncomfortable. Finally, Undyne looked at Papyrus. "...He's a baby?"

Papyrus nodded. **"Yes he is."**

"And you're taking care of him?"

**"Yes I am."**

"...Are you sure about this? Babies are a lot of responsibility and-"

 **"I know! I know!"** Papyrus looked down at Sans, **"I just think that...since I can't trust anyone else, I should be the one to take care of him. I couldn't just leave him out there...He needs me!"**

"He needs an adult!" Undyne argued.

 **"I AM an adult!"** Papyrus argued back.

"YOU'RE 13!"

**"Well, I'm adult enough to LIVE out here!"**

"Can't you just give him to your father?"

 **"And have Sans go through painful experiments his whole life?"** Papyrus asked bitterly. **"I'd rather starve to death!"**

"Ugh..." Undyne began rubbing her temples. "Fine, but he's not gonna last long with the stuff you have right now. I mean, where's his crib? or his clothes?"

Papyrus' expression went blank, he began to think. **"M-maybe he can sleep in a basket?"**

"...I'll tell you what. You can keep that...thing," Undyne said pointing at Sans, "But you're gonna need my help if you want it to live."

 **"I understand, Undyne,"** Papyrus replied. **"But I promise, we'll be all right."**

"Great...now if you'll excuse me, I gotta go look for that thing's parents...or what's left of them."

Papyrus nodded in understanding. Undyne walked through the door frame, which reminded Papyrus that he needed to fix his door later. Sans started to stir, he tapped Papyrus's chest to gain his attention.

 **"Oh, did you need something?"** Papyrus asked, looking down at Sans.The younger skeleton was giving him a curious look. Papyrus sighed as he walked outside. **"Come on, let's go find Doomfanger."**

Sans curled up against Papyrus' chest, he watched as the snow fell through the barrier above them. He could tell that everything was going to be all right.

**Notes for the Chapter:**

> There isn't much in this chapter, so I apologize. However, the next chapter should be fluffy.


	3. Chapter 3

**Notes for the Chapter:**

> So it's been a while since I've updated anything. For that, I apologize. In addition to figuring out what happens next, I hardly had any motivation to write at all. I've gotten a little motivation back, so I should be able to keep going. Additionally, I'm glad that folks like my story. And for that, I thank you guys.

It had been at least an hour since Papyrus left the house, he had been searching everywhere for Doomfanger. As he searched, he was often greeted by the other monsters. Of course, many of them asked about Sans. And while some of them complimented the infant, saying how adorable he was. Other monsters suggested to put him out of his misery, which Papyrus would respond angrily. And besides, why would he want to kill something that did nothing wrong?

Eventually, Papyrus started to walk into Snowdin forest. He wondered if anyone was still at the river bank. Papyrus looked up as he continued to walk, the snow was falling much more gently then it did yesterday. Good, at least now Sans didn't have to cling to him like he did yesterday. Speaking of which, Sans was looking at the snowflakes as well. Of course this would all be new to Sans, especially since he was...well, new. Nonetheless, Papyrus found it adorable.

Finally, the duo made it to the river bank. Undyne was standing there with three of the Royal Guard Dogs, as well as a shadowy figure standing next to the clothes. They were a skeleton monster, they wore a long black robe that reached past their ankles.

**"Did I miss something?"** Papyrus asked as he walked closer. Undyne turned her head, she gave him a concerned look. "I was just about to call you, and...well, it's best if Mono describes what they saw."

**"So YOU saw what happened to Sans' parents?"** Papyrus asked. He gave Mono an odd look as they began to laugh. "And how do you if they were this child's parent?"

**"If they weren't his parents, then where did this dust come from?"** Papyrus asked pointing at the dusty clothes.

"They came from another monster, they out of the lab with this child in their arms," Mono replied. "I can't tell you all of the details. But from what this monster told me, it seems like dear old Dr. Gaster created him."

Papyrus scowled, **"But how? Did another skeleton come into his life?"**

Mono tilted their head. "No...It was more then likely that Dr. Gaster created him artificially. For what reason, I'm not quite sure. But I can tell you one thing, he was furious when the assistant came out. He tried to knock my boat over, but he caused the assistant to fall over with the infant instead. After that...well...I'm sure you know the rest."

"In other words," Undyne said, "Sans is essentially your brother!"

Papyrus was speechless, how couldn't he have seen this earlier? Gaster was the only one who'd choose a name as childish as Comic Sans. Not only that, but Sans almost LOOKED like him, too. Papyrus had guessed that Sans was either created as a guinea pig for his experiments or he was created as a replacement child. Heck, he was probably created for BOTH reasons. Suddenly, a thought had suddenly occurred in Papyrus' skull, he began to grin like a mad man.

**"So...is my father still looking for him?"**

"No he isn't," Mono replied. "He probably thinks that the little one died in the river."

**"Great, so that means I get to keep him as long as he never looks out here!"**

"Right, just make sure they never see each other. Heaven knows what will happen when Dr. Gaster finds him."

**"Understood, thank you."**

Papyrus began to walk back to Snowdin with Undyne walking behind him. As for the dogs, they began to walk back to their stations, as there was no more work to be done here.

 

* * *

 

**"So you're my little brother, huh?"** Papyrus asked as he squeezed Sans' hand. **"You're so small, too."**

"Hey, Papyrus?" Undyne said tugging on Papyrus' scarf, he turned his head. **"Yes, Undyne?"**

"If you want, we could look for a crib right now!"

**"But I don't have the money to buy one,"** Papyrus argued.

"Who needs money when you could just find one at the dump?"

**"We are NOT getting a crib from the dump!"** Papyrus yelled angrily.

"Why not?" Undyne teased.

**"Don't you know that garbage has a lot of diseases? I don't want Sans to get sick!"**

"Psh, those are only human diseases. And besides, I could get someone to clean it up for you."

**"UNDYNE, PLEASE!"**

"Great, then I'll meet you back at your place!"

"UNDYNE!" Papyrus yelled as the fish monster ran ahead of him. Of course, she ignored him. He knew that Sans needed a crib. But even then, he felt that the crib would have to be disinfected in some way or another.

Sans looked up at Papyrus, he began to tug at his scarf. Papyrus looked down at his brother, **"Did you want something?"**

As expected, Sans stared at him blankly.

**"I'm sorry, am I ignoring you?"** Papyrus asked softly. **"How about I give you a warm bath later? Trust me, it'll feel nice after being out here for so long."**

Sans couldn't respond, being an infant. Nonetheless, Papyrus continued to walk until he finally reached his house. When he walked through the door frame, he found Doomfanger was laying down on the couch.

**"Where have YOU been?"** Papyrus asked, **"I've been looking everywhere for you!"**

"Meow!"

**"Yes I was!"** Papyrus argued. He walked into the bathroom and placed Sans into the sink. He put the blanket down in the tub next to him. He turned the tabs slowly while making sure the water was comfortable enough for Sans to sit in. The younger skeleton started to attack the water. Not out of any malice, but out of curiosity.

**"Now here comes the best part,"** Papyrus said as he turned off the water. He reached over to the tub and grabbed a large bottle of bath soap. After he poured the soap into the water, he began to mix it so the sink was full of suds. Papyrus placed some of the suds on Sans' skull, Sans responded by grabbing his hand.

Papyrus grabbed a rag from below the sink, he dipped it in the water and started to rub dirt and dust off of Sans. He didn't want to give the assistant any disrespect, but Sans couldn't keep the dust on him forever.

As time went on, Sans started to doze off. He held onto Papyrus like a security blanket. Papyrus began to notice, he pulled the plug out of the sink and allowed the water to drain. Suddenly, he heard something fall to the floor. He grabbed a towel and wrapped it around Sans before walking out of the bathroom. He saw that Undyne dropped a crib onto the floor. Inside the crib, there were several pink night gowns and onesies.

"Can you believe that someone left a perfectly good crib down here?" Undyne asked, excitedly. "It even came with some clothes!"

**"How convenient,"** Papyrus said, **"But they ARE clean, right?"**

"Don't worry, I asked Woshua to take care of it."

Papyrus grabbed a night gown and sniffed it, it smelled like lilacs. Good, at least SOMEONE cared about keeping everything clean. **"So what should we do, now?"**

"I'm gonna go back to Waterfall," Undyne replied. "In the meantime, you should stay here and keep an eye on Sans."

**"Yes, Undyne."**

"Great, just call me if you need anything."

As soon as Undyne left the house, Papyrus placed Sans onto the couch and began taking the crib to his room. While there was another room he could use upstairs, he figured that it would be best to wait until Sans was old enough to walk. But for now, he was safer in Papyrus' room. Bringing the crib upstairs was a struggle, but he was able to bring it into the middle of his room. Next, he came back downstairs to bring Sans back into his room.

Finally, he put one of the night gowns on Sans. For whatever reason, it was illegal for monsters to wear anything other than black or red. Papyrus could still remember the time when he was scolded by guards for walking outside in green pajamas. But since Pink is technically a lighter shade of red, Sans should be be just fine.

Sans fell asleep in the crib, he looked as though he hadn't slept in days. Papyrus smiled, he spent a moment petting the infant's skull before heading downstairs to make himself some lunch. Suddenly, it occurred to him that he still didn't have any baby bottles for Sans. Perhaps when Sans wakes up, he'll see what he could find at the store.

**Notes for the Chapter:**

> While I personally think that UT!Gaster isn't a bad guy, I'd imagine that UF!Gaster is a little more iffy. But that's something for later.
> 
> This chapter felt a little sluggish, but otherwise I think it's all right.


End file.
